Using the Dart analyzer

When editing Flutter code, it's important to check the code with the analyzer.

If your IDE supports doing this automatically (e.g. using Android Studio with the Flutter plugin), then that is the easiest solution.

Alternatively, you can use the flutter analyze --flutter-repo tool on the console. When using the console, you will want to manually run flutter update-packages each time you update your tree, so that the pubspec.yaml files are processed to obtain all the dependencies for every package in the repository. If you don't do this, you may get bogus error messages about core classes like Offset from dart:ui. This is because flutter analyze does not automatically attempt to update dependencies, since doing so can take a long time and is only necessary when the tree has been updated.

For a one-off, use flutter analyze --flutter-repo.

For continuous analysis, use flutter analyze --flutter-repo --watch.

If you omit the --flutter-repo option you may end up in a confusing state because that will assume you want to check a single package and the flutter repository has several packages.

You can use the --write argument with --watch to cause each update to write all the results to a file in ASCII. This can be used e.g. with Emacs' compile mode to quickly dump all the latest analysis results into the compilation buffer so that they are recognized as error messages that Emacs can jump to.